The present invention generally relates to novel compositions and methods for use thereof in the amelioration of cell death. More specifically, the present invention is directed to peptides obtained from streptokinase, as well as derivatives and analogs thereof, and their use in the amelioration of apoptosis and/or necrosis.
Cell death occurs in both normal human development and in pathological conditions. Two kinds of cell death have been recognized: apoptosis and necrosis. Briefly, apoptosis, or programmed cell death, is a natural process that is triggered by specific biological events and proceeds by well-defined mechanisms. Apoptosis occurs by compaction and convolution of the nuclear chromatin into dense masses, fragmentation of the nucleus, and blebbing of the plasma membrane, ultimately resulting in cell death. Even though 50% of an organism""s cells are experiencing some stage of apoptosis at any given time, the process is observable in only about 0.1% of those cells.
Necrosis, on the other hand, is easily observed. Necrosis results from severe or sudden insult, for example as a result of physical trauma, anoxia, hyperthermia or chemically induced damage. Briefly, necrosis is typified by early changes in the structure and function of the mitochondria. When the mitochondria are unable to provide energy to the cell, the cell can no longer maintain homeostasis. The plasma membrane then loses its ability to regulate osmotic pressure and the cell swells and bursts, spilling its contents into the surrounding tissue and provoking an inflammatory response. In cases of severe injury or bacterial infection, this response can result in additional tissue damage. Cell necrosis is associated with diseases that result from the acute interruption of blood flow to any organ of the body. For example, the interruption of blood flow to the heart, brain, or kidney may produce, by way of example, myocardial infarction, cerebral infarction, or renal infarction, respectively. Cell necrosis is also associated with the toxic effects of bacteria and chemicals and bacterial or viral infections of any organ in the body.
Apoptosis appears to be genetically regulated. However, apoptosis can be induced by exposing cells to radiation, heat, cytotoxic agents, and abnormal changes in cellular biology. The mitochondria may also be involved in apoptosis. Excessive cell death may result in crippling degenerative disorders, for example, the annihilation of vital CD4+ T-lymphocytes in HIV infected patients; the elimination of neurons, and other cell types, following ischemia and reperfusion; and the destruction of cells after exposure to ionizing or ultraviolet radiation in the treatment of neoplastic disorders. These disorders are thought to stem from ectopically programmed cell death, e.g., metabolic or infective factors that induce the apoptosis. Too little cell death can result in proliferative disorders, such as neoplastic disorders or autoimmune disease when a particular immune cell lives beyond its appropriate life span.
One common trigger of apoptosis in the acquisition of these disorders is oxidative stress, which causes the production of free radicals. Free radicals are highly reactive molecular species which interact with a wide variety of naturally occurring cellular components. Exposure to free radical leads to cumulative damage to cellular components and, ultimately, to the tissue itself.
A variety of factors may increase the free radical concentration and oxidative stress, thereby rendering the warm-blooded animal susceptible to cell death and its associated disorders. Such factors include considerations of genetics, nutritional status, exposure to drug therapy, drug metabolism, disease, and environmental factors. A change in any one of these factors may result in a failure of the body""s defensive mechanisms and lead to cell death. Cellular damage has been invoked as a possible etiology in the development of various degenerative disorders, including, by way of example, cardiovascular disease, autoimmune disorders, arthritis, cancer, pancreatitis, hepatoxicity, cataracts, macular degeneration, accelerated aging, Parkinson""s disease, Alzheimer""s disease, and the like.
The present invention discloses novel compositions and methods for the amelioration of cell death, and further provides other related advantages.
As noted above, the present invention provides compositions and methods for the amelioration of cell death due to necrosis or apoptosis. Within one aspect of the present invention peptides obtained from a streptokinase are provided (as well as fragments, derivatives, and analogues thereof), which are capable of ameliorating cell death.
Within a related aspect of the invention, isolated polynucleotide sequences are provided which encode the aforementioned peptide, or a fragment or analogue thereof. Within certain embodiments of the invention, the polynucleotide sequence may be operably linked to a promoter within an expression vector, in order to allow expression of the polynucleotide sequence. Also provided are host cells which contain such expression vectors.
Other aspects of the present invention provide pharmaceutical compositions, comprising a peptide obtained from a streptokinase (as well as fragments, derivatives, and analogues thereof), in a suitable pharmaceutical, physiological, or medicamentally acceptable excipient or diluent.
Within yet another aspect of the present invention, methods of ameliorating cell death are provided comprising the general step of treating a warm-blooded animal by administering a therapeutically effective amount of a compound, as described above, such that cell death is ameliorated. In this regard the compound may be either a peptide or peptide derivative, a peptide analog, or, a nucleic acid molecule which directs the expression of the peptide or peptide derivative. In one embodiment of this aspect, the warm-blooded animal is suffering from a disorder selected from the group consisting of neurodegenerative disorders, cardiovascular diseases, immune diseases, neoplastic disorders, inflammatory disorders, myelodegenerative disease, viral disease and degenerative diseases of any organ.
Neurodegenerative disorders include, by way of example, Parkinson""s, Alzheimer""s, Huntington""s, cerebellar degeneration, and FALS.
Cardiovascular diseases include, by way of example, hypertensive heart disease, heart failure, atherosclerosis, myocardial infarction, congestive heart disease and myocardial reperfusion injury.
Immune diseases include, by way of example, autoimmune disease, AIDS/HIV, and immune deficiencies. Autoimmune diseases include, by way of example, rheumatoid arthritis, systemic lupus erythematosus, insulin-dependent diabetes mellitus, myasthenia gravis, glomerulonephritis, lupus, pernicious anemia, dermatomyositis, enythema nodosum, Sjxc3x6gren""s syndrome, temporal arteritis, Wegener""s granulomatosis, antiphospholipid syndrome, and autoimmune polyarthritides.
Neoplastic disorders include, by way of example, leukemia, sarcomas, myelomas, carcinomas, neuromas, melanoma, cancers of the breast, brain, colon, cervix, or prostrate, Hodgkin""s disease, and non-Hodgkin""s lymphoma.
Inflammatory diseases include, by way of example, inflammatory joint disorders, arthritis, and inflammatory-induced cell damage to eye, brain, and other organs. Viral diseases include, by way of example, viral infections, such as hepatitis, retroviral infections, and viral encephalitis. Other disorders include macular degeneration, cataracts, pancreatitis, Crohn""s disease, ulcerative colitis, and accelerated aging.
In another aspect of the present invention, the warm-blooded animal is suffering from an insult selected from the group consisting of physical trauma, anoxia, hyperthermia, chemically-induced damage, and radiation-induced damage.
In still yet another aspect of the present invention, the warm-blooded animal has been subjected to a procedure selected from the group consisting of bypass surgery, chemotherapy, and organ transplantation.
These and other aspects of the present invention will become evident upon reference to the following detailed description and attached drawings. In addition, various references are set forth below which describe in more detail certain procedures or compositions (e.g., plasmids, etc.), and are therefore incorporated by reference in their entirety as if each were explicitly incorporated herein.